Chapter 6. Clinical Pharmacology of Local Anesthetics
Which of the following is true regarding the history of local anesthetics (LAs)?
A. Cocaine was the first applicable product used by Carl Koller as a LA.
B. Ten years after the first introduction of cocaine as a LA, the first successful brachial plexus block was performed.
C. Leonard Corning was the first to perform a spinal anesthesia with cocaine.
D. Esters occur naturally. The first synthetic local anesthetic was an amide like lidocaine, which was introduced almost 100 years later.
A is correct. Carl Koller and Joseph Gartner used cocaine to produce topical anesthesia of the conjunctiva. The birth of local and regional anesthesia dates from 1884, when Koller and Gartner reported their success at producing topical cocaine anesthesia of the eye in the frog, rabbit, dog, and human.
B is incorrect. Only one year after the first introduction of cocaine as a LA, the first successful brachial plexus block was performed.
C is incorrect. August Bier was the first person to use cocaine for spinal anesthesia.
D is incorrect. Only cocaine is a natural occurring local anesthetic ester. Others are synthetic variants. The first introduction of an amide was in 1948, around 70 years later.
Voltage-gated sodium (Na) channels have a specific structure. Which of the following statements is true?
A. They consist of two large α-subunits and two smaller β-subunits. The β-subunit is the place of LA binding, causing a blockade in neural excitability and impulse transmission between neural fibers.
B. They consist of six transmembranous segments. A shift in these segments causes inadequate transmission of neurotransmitters causing an inexcitable neuron.
C. They consist of one α-subunit and two β-subunits. The α-subunit is the site of ion conduction and of LA binding. Sodium channels have at least three native configurations.
D. The distribution between sodium channels in myelinated and unmyelinated fibers is the same. The difference in conduction mechanism causes LA to be more potent in the unmyelinated nerve fibers.
C is correct. They consist of one α-subunit and two β-subunits. The α-subunit is the site of ion conduction and of LA binding. Sodium channels have at least three native configurations.
A is incorrect. Sodium (Na) channels consist of one large α-subunit and two smaller β-subunits in humans. The α-subunit is the place of local anesthetic binding.
B is incorrect. The α-subunit has four homologous domains, each with six ...